Extract build configuration into a separate header and move it to the base lib

Extract build configuration into a separate header and move it to the base lib

With this, change, atomicops, once, and lazy instance are no longer dependant
on v8 core. I'll move them in a follow-up change to the libbase as well.

BUG=none
R=jkummerow@chromium.org
LOG=n

Committed: https://code.google.com/p/v8/source/detail?r=21546

[Jakob Kummerow, 2014-05-28 07:55:10]

lgtm

[jochen (gone - plz use gerrit), 2014-05-28 08:07:29]

Committed patchset #1 manually as r21546 (presubmit successful).